The present invention relates to a radioactive waste treatment facility for solidification of radioactive waste, which is generated from radioactive material handling facilities such as nuclear power plants, fuel reprocessing plants, and the like.
The radioactive waste generated from radioactive material handling facilities such as nuclear power plants, fuel reprocessing plants, and the like is generally solidified with a hydraulic solidifying material such as cement and the like. In accordance with the above processing, not only the volume of the radioactive waste can be reduced, but also stable a solidified waste superior in long term duration can be obtained.
Generally, the radioactive waste is classified to various groups having different properties each other such as miscellaneous solid waste, concentrated liquid waste, spent resin, ashes, and others. Respective of the groups is handled with an appropriate treating method of injecting solidification or kneading solidification depending on its kind and properties.
The injecting solidification is a method, in which the waste is contained in a drum first, and then, a solidifying agent is injected into the drum from the top of the drum for solidification. The injecting solidification method is applied to incombustible miscellaneous solid waste such as pipes and others, with which the solidifying agent can be flowed down through intervals among the solid waste.
The kneading solidification is a method, in which the waste is solidified by kneading with a solidifying agent. The kneading solidification method is applied to powder, granular, or liquid waste such as concentrated liquid waste and its dried powder, spent resin, ashes, and the like. At this time, there are in-drum type and out-drum type for the kneading method. The in-drum type method is a method, in which, after charging the waste and a solidifying agent together into a solidifying container (or during charging), a kneading blade is inserted into the charged materials to knead them. The out-drum type method is a method, in which, after charging the waste and a solidifying agent together into an exclusive kneading container and kneading the charged materials by inserting a kneading blade therein, the kneaded material is poured into a solidifying container.
As explained above, the injecting solidification and the kneading solidification are different solidification methods each other. Therefore, in order to treat miscellaneous many kind radioactive wastes adequately, an appropriate solidification facility must be provided respectively, and a significantly broad installation site area was required.
In order to solve the above problem, a radioactive waste treatment facility (solidification facility) comprising; a transferring means for transferring solidifying containers; an out-drum mixer type kneader which is capable of preparing kneaded material by charging a solidifying agent, additive water, and the radioactive waste together therein and kneading them; and a kneaded material injecting means, which injects the kneaded material into a solidifying container at a designated location in the transferring direction of the transferring means; is disclosed in JP-A-8-29594 (1996).
In accordance with the radioactive waste treatment facility, when performing the injection and solidification of the radioactive miscellaneous solid waste and others, a solidifying container wherein the radioactive waste is supplied previously is transferred to a designated location by the transferring means; only the solidifying agent and the additive water are charged into the kneader to prepare a solidifying agent paste; and the solidifying agent paste is injected into the solidifying container by the kneaded material injecting means. Accordingly, the solidifying agent paste is flowed down through the intervals among the solid waste to be filled into the solidifying container, and a solidified waste as same as the one obtained by a normal injecting solidification method can be prepared.
On the other hand, when concentrated liquid waste, spent resin, ashes, and the like are solidified by the kneading solidification, a solidified waste (homogeneous solidified waste), wherein the solidifying paste and the radioactive waste are mixed thoroughly, as same as the one obtained by a normal injecting solidification method can be prepare by the steps of: transferring an empty solidifying container to a designated location by the transferring means; charging a solidifying agent, additive water, and the radioactive waste into a kneading vessel of the kneader; agitating the charged material with kneading blade to form a kneaded material; and injecting the kneaded material into the solidifying container by the kneaded material injecting means.
In accordance with the prior art described above, kneading the solidifying paste (solidifying agent+additive water) for kneading solidification, and kneading the kneaded material for kneading solidification are performed by a similar out-drum-mixer type kneader, in order to make it possible to perform injecting solidification and kneading solidification together by a single facility.
However, in accordance with the above prior art, the following problems are still remained to be solved.
That is, the radioactive waste treating (solidification) facility must be cleaned up after completing a designated treatment. At that time, the portions touched with the radioactive water are contaminated with radioactive material, and washed water of the portions become secondary radioactive waste and another treating facility for the secondary radioactive waste becomes necessary. Accordingly, in the radioactive waste treating (solidification) facility, it is preferable that the portions touched with radioactive waste must be reduced as small as possible.
Generally, in case of out-drum type kneader is used in the kneading solidification, both the kneading blade and the kneading vessel are contaminated with radioactive material, and both of them must be washed. On the contrary, in case of in-drum type kneader is used, only the kneading blade is contaminated. Therefore, only the kneading blade must be washed, and the amount of secondary radioactive material can be reduced.
In accordance with the prior art, the out-drum mixer type kneader is used, in order to make it possible to perform injecting solidification and kneading solidification together by a single facility. Accordingly, both the kneading blade and the kneading vessel are contaminated with radioactive material in the kneading solidification operation, and both of them must be washed. Therefore, the amount of the secondary radioactive waste can be hardly reduced.
One of the objects of the present invention is to provide a radioactive waste treatment facility, which can perform both the injecting solidification and the kneading solidification together by a single facility, and makes it possible to reduce the generating amount of the secondary radioactive waste.
(1) In order to achieve the above object, the radioactive waste treatment facility of the present invention comprises;
a transferring means for transfer a solidifying container;
a solidifying agent kneading and injecting means for preparing a solidifying agent paste by kneading the solidifying agent and additive water, and injecting the solidifying agent paste into the solidifying container at a first location in the upstream of the transferring direction of the transferring means; and
a waste charging and kneading means for charging the radioactive waste into the solidifying container at a second location in the downstream, in comparison with the first location, of the transferring direction of the transferring means, and kneading the radioactive waste with the solidifying paste in the solidifying container.
In accordance with the radioactive waste treatment facility of the present invention composed as described previously, when the injecting solidification of radioactive miscellaneous solid waste is performed, a solidifying container, wherein the radioactive waste is charged previously, is transferred to the first location by the transferring means, and the solidifying paste is injected into the solidifying container by the solidifying agent kneading and injecting means. Therefore, as the solidifying paste is filled into the solidifying container by flowed down through the intervals among the radioactive waste, a solidified waste as same as the one obtained by the normal injecting solidification can be prepared.
On the other hand, when the kneading solidification of radioactive concentrated liquid waste, spent resin, ashes, and others is performed, an empty solidifying container is transferred to the first location by the transferring means, and only the solidifying paste is injected into the solidifying container by the solidifying agent kneading and injecting means. Subsequently, the solidifying container is transferred to the second location; the radioactive waste is charged into the solidifying container, wherein the solidifying paste is filled previously, by the waste charging and kneading means at the second location; and kneading is performed in the solidifying container. Accordingly, a solidified waste (homogeneous solidified waste), the solidifying paste and the radioactive waste are mixed thoroughly, as same as the one obtained by the normal injecting solidification can be prepared.
In accordance with the composition described above, the injecting solidification and the kneading solidification can be performed by a single facility, and the solidifying agent kneading and injecting means can be made the out-drum type and the waste charging and kneading means can be made in-drum type.
At that time, the solidifying agent kneading and injecting means is used for kneading only the non-radioactive solidifying agent and the non-radioactive additive water. Therefore, the solidifying agent kneading and injecting means can be installed in an area separated by, for instance, a separation wall from the area where the waste charging and kneading means is installed. Because the liquid waste of washing is also non-radioactive, and it could be readily treated and deposited. On the other hand, the waste charging and kneading means is charged with radioactive waste when kneading and solidifying. Therefore, the liquid waste from washing the waste charging and kneading means becomes the secondary radioactive waste. However, the waste charging and kneading means can be made in-drum type, and washing is necessary only for kneading blade. Accordingly, the generating amount of the secondary radioactive waste can be reduced.
(2) In accordance with the above methods described in (1), the solidifying agent kneading and injecting means desirably comprises;
a kneading vessel, whereto the solidifying agent and the additive water is charged;
a first kneading blade for agitating inside of the kneading vessel;
an out-drum type kneader for preparing the solidifying agent paste; and
an injecting means for injecting the solidifying agent paste in the kneader for preparing the solidifying agent paste into the solidifying container.
(3) In accordance with the above methods described in (1), the waste charging and kneading means desirably comprises;
an elevating means for elevating the solidifying container, which has been transferred to the second location by the transferring means, upward from the transferring line of the transferring means; and
an in-drum type radioactive waste kneader, which charges the radioactive waste into the elevated solidifying container and performs kneading in the solidifying container with the second kneading blade.
(4) In accordance with the above methods described in (1), the solidifying agent injecting and kneading means is desirably provided in an area separated from the waste charging and kneading means by separating walls.